30 lines
797 B
Markdown
30 lines
797 B
Markdown
---
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title: Linear search
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tags: algorithm,array
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expertise: beginner
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author: maciv
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firstSeen: 2020-12-28T12:07:53+02:00
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lastUpdated: 2020-12-28T12:07:53+02:00
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---
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Finds the first index of a given element in an array using the linear search algorithm.
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- Use a `for...in` loop to iterate over the indexes of the given array.
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- Check if the element in the corresponding index is equal to `item`.
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- If the element is found, return the index, using the unary `+` operator to convert it from a string to a number.
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- If the element is not found after iterating over the whole array, return `-1`.
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```js
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const linearSearch = (arr, item) => {
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for (const i in arr) {
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if (arr[i] === item) return +i;
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}
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return -1;
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};
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```
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```js
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linearSearch([2, 9, 9], 9); // 1
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linearSearch([2, 9, 9], 7); // -1
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```
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